[Lord Molyb]

North skillfully wrapped up his grand slam contract. Afterwards he noted that he could still make a grand slam if the south hand was switched with either of the east/west hands, and there were no suits longer than 9 cards.
What's the weakest hand north could have that makes these statements true?

[Fluffy]

you mean same grand slam or any grand slam?

[ggwhiz]

How about 10 solid and 3 aces

[Fluffy]

if 10>9 I bet not , anyway AK8th AKQ5th is cheaper.

Even cheaper is AKxxxxx/AKxxxx, the 6 card suit is the side suit, one player has the queen doubleton to make all, another 3 cards, and the last one ruffs the third round with queen of trumps.

For finessing issues OP should define better where does anyone sit when they switch positions.

[Lord Molyb]

Fluffy, on 2014-January-20, 15:42, said:

you mean same grand slam or any grand slam?

any grand is fine

[Lord Molyb]

Fluffy, on 2014-January-20, 15:58, said:

if 10>9 I bet not , anyway AK8th AKQ5th is cheaper.

Even cheaper is AKxxxxx/AKxxxx, the 6 card suit is the side suit, one player has the queen doubleton to make all, another 3 cards, and the last one ruffs the third round with queen of trumps.

For finessing issues OP should define better where does anyone sit when they switch positions.

A grand slam makes as the cards are, or if the south cards/player are switched with the west cards/player, or if south is switched with east.

[Hanoi5]

♠AK
♥AK
♦AK
♣AKxxxxx

Each of South, East and West hold 7-card suits.

[Fluffy]

Then something like AQxxxxx and AKxxxx should be enough, RHO of declarer has Kx of trumps and xxx in the side suit, others have Jack of trumps with doubleton side (entry ruffing with the jack) or the queen of the side suit.

[nige1]

Lord Molyb, on 2014-January-20, 15:13, said:

North skillfully wrapped up his grand slam contract. Afterwards he noted that he could still make a grand slam if the south hand was switched with either of the east/west hands, and there were no suits longer than 9 cards.
What's the weakest hand north could have that makes these statements true?

Just to get the ball rolling

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[kayin801]

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Got it down to 10 HCP?

[nige1]

Deleted

[nige1]

kayin801, on 2014-January-20, 21:47, said:

Got it down to 10 HCP?

kayin801 really got it down to 9 HCP but I'm sure we can do better

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[nige1]

7 HCP?
This can probably be improved on. Possibly by a lot, if we consider grand-slams in three different denominations

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[Lord Molyb]

I tried:

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With the south hand north can make 7♠ by ruffing a heart. If you switch south and east, you can make 7 hearts by ruffing three spades, and if you switch south and west, you can make 7♥ by pitching 5 spades on 3 diamond and 2 club winners.
As I have seen, this is not the correct answer

[Lord Molyb]

5 HCP! Only North has to make it, as was specified in the original post.

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As the cards are, on a plain suit lead north simply ruffs, draws 2 trumps ending in dummy, and discards all his diamonds on the clubs.
Switch south and west and the play is trivial- draw trumps and everything is good. The defense can't get a ruff because the diamond void is on lead.
Switch south and east, and 7♠ still makes. The best leads, a diamond and a trump, are both won by the ♠K and all of North's diamonds disappears on the top hearts.

[nige1]

I doubt anybody can improve on Molyb's effort. With one trump suit, can anyone get it down to 5 HCP?

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[Lord Molyb]

I think this one wins for three different suits.

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Opposite of any of the hands, a thirteen card fit exists and a grand slam makes on a crossruff.